I bought myself a book for Christmas (Mark Forsyth's A Christmas Cornucopia) and then, immediately after it arrived from Amazon, read the whole thing in one evening. I enjoyed it so much that I thought I might actually share the bit about Santa with you here at ITBB, but, as the author has now posted a potted retake of his Santa chapter over at the Spectator, I won't bother.
Instead, I'll do something about Hark! The Herald Angels Sing, famously with words by Charles Wesley and music by Felix Mendelssohn - except that...
(a) Wesley was aghast that his original words "Hark how all the welkin rings/Glory to the King of Kings" had been changed (by a preacher called George Whitfield) to "Hark, the herald angels sing/Glory to the new-born King!". The Bible insisted that the herald angels said their news rather than sung it to the abiding shepherds, so Mr Wesley said that he didn't want to be held "accountable either for the nonsense or the doggerel of other men".
(b) Mendelssohn died without ever hearing the hymn. His tune - the tune we know - had been written for a cantata commemorating the 400th anniversary of the Gutenberg press. He realised that he'd written a good tune and said that people could add new words to it just as long as they weren't religious words. And then someone (William Cummings) went right against his wishes, after his death, and fitted them to Whitfield's "doggerel".
And ever since then people have been carolling away unaware that they are going against the explicit, written wishes of both the lyricist and the composer.